1. Field of the Invention
The present invention relates to a hollow profile formed of a flat material and having a plurality of side walls and at least one groove provided on an outer side of at least one of the plurality of side walls and having a bottom spaced form the outer side by a predetermined depth and two opposite side walls.
The present invention also relates to a method of forming the hollow profile.
2. Description of the Prior Art
Generally, a hollow profile, which is formed of a flat material, is characterized by a small weight while having good static characteristics. For positioning and guiding of connection, parts, e.g., add-on parts, a hollow profile of an assembly system is provided with grooves in which the connection parts are guided. With add-on components being mounted on a hollow profile, often, torsional loads act on the hollow profile. Therefore, from a static point of view, a circumferentially closed hollow profile is preferred. However, the greater is the depth of the groove the smaller is the torsional load a hollow profile can withstand. Therefore, it is desirable to have the groove depth as small as possible.
As a rule, the size of the inner bending radius of a sheet, which is bent to 90°, corresponds to the thickness of the sheet. The drawback of this general rule consists in that with a small groove depths, which are accompanied by small bending radii, it is impossible to obtain side walls of a groove which would extend perpendicular to the groove bottom or to the outer side of a profile. The use of a narrow bending radius corresponding to the thickness of a flat material is accompanied by upsetting of the flat material on the inner side of a bent and by stretching of the flat material on the outer side of the bent. This leads to formation of fissures and/or reduction of the material strength.
It is known to form notches before bending at the position of the inner radius of a material. The formation of notches permits to use radii as small as the thickness of the flat material. However, this results in reduction of the cross-section of the material and, consequently, in reduction of the material strength.
Up to the present, with grooves having a small radius, this problem was bypassed by forming a groove with side walls extending to the groove bottom at angle different from 90°, e.g., at an angle of 45°. If a connection part with rectangular bearing surfaces is loaded sidewise, with such a groove, its guidance in the longitudinal direction of a profile and the prevention of the part from rotation is not insured. When the bearing surface of a connection part is complementary to the shape of a groove, with a side load acting on the connection part, a force component would be produced that would extend at an angle to the direction of force acting on the connection part and that could lift the connection part out of the groove.
Accordingly, an object of the present invention is to provide a hollow profile from a flat material with a groove having a small depth and which would insure an adequate longitudinal and lateral guidance for a connection part, whereby the absorption of the torsional stresses would be insured.
Another object of the present invention is to provide a hollow profile that can be produced simply and economically.